Semiconductor package substrates typically function as intermediate structures between an integrated circuit and a device substrate, e.g., a printed circuit board. A semiconductor package substrate supports the integrated circuit and transmits electrical signals between the integrated circuit and the device substrate through various conductors, e.g., conductive traces or vias. The semiconductor package substrate may include alternating layers of conductive and insulating layers, and the conductive layers are generally patterned to form the conductors. The layers of the semiconductor package substrate are typically deposited and/or laminated on one another.
A surface preparation process known as a “desmear” process may be used to roughen an insulating layer prior to depositing a conductive layer on the insulating layer. The roughened surface of the insulating layer is intended to enhance adhesion between the conductive and insulating layers. More particularly, the surface preparation is intended to promote mechanical adhesion by creating a rough surface such that the conductive layer anchors to the insulating layer. Thus, the desmear process is usually tuned to maximize mechanical adhesion.